import math
x1,y1,x2,y2=map(float,input().split())
dx=abs(x1-x2)
dy=abs(y1-y2)
print(math.sqrt(dx*dx+dy*dy)) import math math x1,y1,x2,y2=map(float,input().split()) x1 map(float,input().split()) map float input().split() ().split () input split y1 x2 y2 dx=abs(x1-x2) dx abs(x1-x2) abs x1-x2 x1 x2 dy=abs(y1-y2) dy abs(y1-y2) abs y1-y2 y1 y2 print(math.sqrt(dx*dx+dy*dy)) print math.sqrt(dx*dx+dy*dy) math.sqrt math sqrt dx*dx+dy*dy dx*dx dx dx dy*dy dy dy dy=abs(y1-y2) abs(y1-y2) dy x2,y2=map(float,input().split()) map(float,input().split()) x2 y1,x2,y2=map(float,input().split()) map(float,input().split()) y1 y2=map(float,input().split()) map(float,input().split()) y2 dx=abs(x1-x2) abs(x1-x2) dx x1,y1,x2,y2=map(float,input().split()) map(float,input().split()) x1
import math
x1,y1,x2,y2=map(float,input().split())
dx=abs(x1-x2)
dy=abs(y1-y2)
print(math.sqrt(dx*dx+dy*dy))